{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,10]],"date-time":"2026-10-10T15:07:15Z","timestamp":1791644835944,"version":"4.3.4"},"reference-count":27,"publisher":"Oxford University Press (OUP)","issue":"6","funder":[{"DOI":"10.13039\/100000030","name":"Centers for Disease Control and Prevention","doi-asserted-by":"publisher","id":[{"id":"10.13039\/100000030","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100000875","name":"Clinical and Translational Science Award","doi-asserted-by":"publisher","award":["UL1 TR002243"],"award-info":[{"award-number":["UL1 TR002243"]}],"id":[{"id":"10.13039\/100000875","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100006108","name":"National Center for Advancing Translational Sciences","doi-asserted-by":"publisher","id":[{"id":"10.13039\/100006108","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100000002","name":"NIH","doi-asserted-by":"publisher","id":[{"id":"10.13039\/100000002","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2023,3,21]]},"abstract":"<jats:title>Abstract<\/jats:title>\n               <jats:sec>\n                  <jats:title>Background<\/jats:title>\n                  <jats:p>The COVID-19 pandemic was associated with historically low influenza circulation during the 2020\u20132021 season, followed by an increase in influenza circulation during the 2021\u20132022 US season. The 2a.2 subgroup of the influenza A(H3N2) 3C.2a1b subclade that predominated was antigenically different from the vaccine strain.<\/jats:p>\n               <\/jats:sec>\n               <jats:sec>\n                  <jats:title>Methods<\/jats:title>\n                  <jats:p>To understand the effectiveness of the 2021\u20132022 vaccine against hospitalized influenza illness, a multistate sentinel surveillance network enrolled adults aged \u226518 years hospitalized with acute respiratory illness and tested for influenza by a molecular assay. Using the test-negative design, vaccine effectiveness (VE) was measured by comparing the odds of current-season influenza vaccination in influenza-positive case-patients and influenza-negative, SARS-CoV-2\u2013negative controls, adjusting for confounders. A separate analysis was performed to illustrate bias introduced by including SARS-CoV-2\u2013positive controls.<\/jats:p>\n               <\/jats:sec>\n               <jats:sec>\n                  <jats:title>Results<\/jats:title>\n                  <jats:p>A total of 2334 patients, including 295 influenza cases (47% vaccinated), 1175 influenza- and SARS-CoV-2\u2013negative controls (53% vaccinated), and 864 influenza-negative and SARS-CoV-2\u2013positive controls (49% vaccinated), were analyzed. Influenza VE was 26% (95% CI: \u221214% to 52%) among adults aged 18\u201364 years, \u22123% (\u221254% to 31%) among adults aged \u226565 years, and 50% (15\u201371%) among adults aged 18\u201364 years without immunocompromising conditions. Estimated VE decreased with inclusion of SARS-CoV-2\u2013positive controls.<\/jats:p>\n               <\/jats:sec>\n               <jats:sec>\n                  <jats:title>Conclusions<\/jats:title>\n                  <jats:p>During a season where influenza A(H3N2) was antigenically different from the vaccine virus, vaccination was associated with a reduced risk of influenza hospitalization in younger immunocompetent adults. However, vaccination did not provide protection in adults \u226565 years of age. Improvements in vaccines, antivirals, and prevention strategies are warranted.<\/jats:p>\n               <\/jats:sec>","DOI":"10.1093\/cid\/ciac869","type":"journal-article","created":{"date-parts":[[2022,11,3]],"date-time":"2022-11-03T18:38:17Z","timestamp":1667500697000},"page":"1030-1037","source":"Crossref","is-referenced-by-count":26,"title":["Vaccine Effectiveness Against Influenza A(H3N2)\u2013Associated Hospitalized Illness: United States, 2022"],"prefix":"10.1093","volume":"76","author":[{"given":"Mark W","family":"Tenforde","sequence":"first","affiliation":[{"name":"Influenza Division, Centers for Disease Control and Prevention , Atlanta, Georgia , USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Manish M","family":"Patel","sequence":"additional","affiliation":[{"name":"Influenza Division, Centers for Disease Control and Prevention , Atlanta, Georgia , USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Nathaniel 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Emergency Medicine, Beth Israel Deaconess Medical Center , Boston, Massachusetts , USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Abhijit","family":"Duggal","sequence":"additional","affiliation":[{"name":"Department of Medicine, Cleveland Clinic , Cleveland, Ohio , USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Matthew E","family":"Prekker","sequence":"additional","affiliation":[{"name":"Departments of Emergency Medicine and Medicine, Hennepin County Medical Center , Minneapolis, Minnesota , USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ithan D","family":"Peltan","sequence":"additional","affiliation":[{"name":"Department of Medicine, Intermountain Medical Center, Murray, Utah and University of Utah , Salt Lake City, Utah , USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"David N","family":"Hager","sequence":"additional","affiliation":[{"name":"Department of Medicine, Johns Hopkins University School 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H","family":"Kwon","sequence":"additional","affiliation":[{"name":"Department of Medicine, Washington University , St Louis, Missouri , USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"James D","family":"Chappell","sequence":"additional","affiliation":[{"name":"Department of Pediatrics, Vanderbilt University Medical Center , Nashville, Tennessee , USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Natasha","family":"Halasa","sequence":"additional","affiliation":[{"name":"Department of Pediatrics, Vanderbilt University Medical Center , Nashville, Tennessee , USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Adam S","family":"Lauring","sequence":"additional","affiliation":[{"name":"Departments of Internal Medicine and Microbiology and Immunology, University of Michigan , Ann Arbor, Michigan , USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Christopher 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